Fly Strike in Sheep: Prevention and Welfare

Fly strike, caused by blowfly maggots burrowing into living sheep flesh, is a painful and often fatal condition that affects millions of sheep annually in the UK and Australia.

Key Facts

Fly strike affects an estimated 3% of UK sheep annually, causing significant mortality
The primary cause is Lucilia sericata, the green bottle fly, which lays eggs on damp fleece
Early detection is critical but the cryptic nature of early lesions makes this difficult
Preventive chemical treatments can cause environmental harm to invertebrates
Breeding for low-wrinkle skin and shorter fleece reduces susceptibility significantly

Welfare Considerations

Fly strike causes intense suffering. Maggots secrete enzymes that liquefy tissue, causing rapidly spreading wounds that are extremely painful. Affected sheep may show little outward sign until the condition is advanced. Shepherd vigilance during warm and wet conditions is essential, but the practical challenge of checking large numbers of sheep makes prevention through breeding and targeted treatment particularly important. Mulesing — surgical removal of skin folds around the tail — is performed without anaesthesia in Australia and is a significant welfare concern.

What You Can Do

Support breeding programmes that select for natural fly-strike resistance
Advocate for pain relief to be mandatory for mulesing procedures
Choose wool from certified fly-strike-prevention programmes
Support research into vaccine-based alternatives to chemical prevention
Encourage farmers to invest in regular checking and early intervention systems